High-Dose 131I-Tositumomab (Anti-CD20) Radioimmunotherapy for Non-Hodgkin’s Lymphoma: Adjusting Radiation Absorbed Dose to Actual Organ Volumes

Article Figures & Data

TABLE 1

Dosimetry Estimate Results of Biodistribution Studies After Trace Dose of ¹³¹I-Tositumomab Using MIRD Method (n = 84)

Organ	Mean residence time* (h)	Mean absorbed dose* (mGy/MBq)	Mean CT volume* (mL)
Lungs	9.03 (4.5–13.6)	1.67 (0.81–4.32)	1,371 (528–5,810)
Liver	12.4 (5.8–21.9)	1.03 (0.57–1.67)	1,782 (662–3,420)
Spleen	2.17 (1.38–4.89)	1.08 (0.19–1.97)	316 (50–639)
Kidneys	1.7 (0.81–3.88)	2.67 (0.32–4.40)	381 (230–661)
Whole-body mass	62.4 (30.4–87.8)	0.30 (0.16–0.38)	82.85 (57–134)^†

TABLE 2

Residence Times in Major Source Organs Estimated from Biodistribution Studies: MIRD Volume Versus Adjusted for Actual Volume (n = 84)

Organ	MIRD model mean residence time* (h)	Actual volume mean residence time* (h)	r	P value
Lungs	11.7 (1.3–22.9)	9.4 (4.3–16.6)	0.49	0.0001
Liver	11.7 (4.7–17.6)	12.5 (5.8–21.9)	0.64	0.004
Kidneys	2.2 (0.8–4.1)	1.9 (0.8–8.2)	0.45	0.0004
Spleen	3.4 (0.3–6.2)	2.2 (0.3–5)	0.22	0.0001
Whole body	78.5 (40–107.7)	70.1 (30.4–114)	0.78	0.0001

TABLE 3

Radiation Absorbed Dose to Organs Estimated from Biodistribution Studies: MIRD Volume Versus Actual Volume

Organ	MIRD model radiation absorbed dose* (mGy/MBq)	Actual volume radiation absorbed dose* (mGy/MBq)	r	P value
Lungs	1.67 (0.81–4.32)	1.30 (0.19–2.56)	0.71	0.0001
Liver	1.03 (0.57–1.67)	0.92 (0.24–2.22)	0.72	0.01
Kidneys	1.08 (0.19–1.97)	0.76 (0.18–4.81)	0.81	0.0001
Spleen	2.67 (0.32–4.40)	1.40 (0.081–5.18)	0.29	0.0001
Whole body	0.30 (0.16–0.38)	0.22 (0.022–0.40)	0.65	0.0001